At present, a wide variety of conductor splicing electrical connectors are used in telephone systems. Generally, these connectors comprise at least two separate and distinct elements, is namely, an index strip and a connector module. U.S. Pat. No. 3,798,587 to B. C. Ellis, Jr. et al. ("'587 patent") discloses one such typical wire connecting blocks, wherein the index strip has a plurality of teeth of alternating height which are spaced-apart, and the connector module has a plurality of slotted insulation displacement connectors and a plurality of teeth of alternating height and spaced-apart, identical to those of the index strip. The '587 patent discloses electrical connections between two sets of conductors are accomplished by first placing the first set of conductors along slots between the spaced-apart teeth of the index strip and the second set of conductors between slots of the insulation displacement connectors of the spaced-apart teeth of the connector module. Then the connector module is placed over the index strip, with the slotted insulation displacement connectors making electrical connection between the first and second set of conductors by penetrating the insulation.
U.S. Pat. No. 4,118,095 to R. N. Berglund et al. ("'095 patent") discloses an improved two-element wire connecting block. Significantly, the '095 patent modifies the connector module disclosed in the '587 patent to facilitate alignment of the slotted insulation displacement connectors and to provide an integral skirt for maintaining electrical isolation of the end of the first set of conductors to minimize short circuits between conductors.
Further improvement of the two-element system is the addition of a third element, a cap module, as disclosed in U.S. Pat. No. 3,772,635 to D. R. Frey et al. ("'635 patent") and U.S. Pat. No. 4,262,985 to A. A. Muehlhausen II ("'985 patent"). The '635 patent discloses a cap module, for use with a modified index strip and a modified connector block, which serves the purpose of snubbing the second set of conductor ends. The '985 patent discloses a cap module capable of gripping, snubbing and isolating the second set of conductor ends. The cap module of both the '635 and the '985 patents are snap-mounted onto the connector module with a latch-hole interlocking mechanism.
Normally the assembly of the wire connecting blocks disclosed in these patents require an expensive tool such as that disclosed in the '635 patent and U.S. Pat. No. 3,898,724 to T. A. Conorich ("'724 patent"). The seating tool is used to trim and properly snub the conductors into slots between the spaced-apart teeth of the wire connecting blocks to achieve electrical connections.
U.S. Pat. Nos. 3,772,635, 3,798,587, 3,898,724, 4,118,095 and 4,262,985 discussed above are hereby incorporated by reference as background of the invention.
Prior art wire connecting blocks described above are suitable for installation and for rearrangement of a large-scale telephone system because typical index strips, connector modules and seating tools are designed to make multiple pairs of electrical connections at one time. Once a telephone system had been properly installed and all electrical conductors pre-connected, rearrangement of a large-scale network interface unit require a visit from a skilled telephone service technician, who can work through the complex maze of telephone connections and is likely to possess an expensive seating tool for making efficient and effective connections. Rearrangement of a large-scale network interface unit justifies a visit from a telephone service technician or the purchase of a seating tool, which can be time consuming and costly.
When rearrangement of a network interface unit involves only a few electrical connections, it does not justify the cost of purchasing an expensive seating tool or requiring a visit from a telephone service technician. However, with prior art wire connecting blocks, such a task cannot be effectively accomplished without the assistance of a seating tool or a telephone service technician, adding materially to the cost and time expended.
In order to rearrange electrical connections of a telephone system, it is necessary to first trace the telephone connections to the connector module located in the network interface unit, disassemble the electrical connections from the slots of the connector module and then reassemble the electrical connections at slots corresponding to the desired connections on the index strip.
Prior art wire connecting blocks contain a number of shortcomings when handled by an inexperienced person. For example, the two-element prior art wire connecting block does not provide a reliable positive grip of the electrical conductors to allow secure tracing of the wires. The two-element wire connecting block also provides minimum to no electrical isolation of the conductor ends. Furthermore, proper use of the two-element wire connecting block requires an expensive seating tool. On the other hand, while a three-element prior art wire connecting block eliminates some of these drawbacks, it requires the removal of the cap module before the removal of the electrical connections from the connector module. Such a cap module is generally snap mounted onto the connector module by way of a spring-latch-hole interlocking feature, making its removal difficult. Even if removal of the cap module is successful, it can be easily lost or misplaced.
It is therefore the aim of this invention to provide an improved index strip for a wire connecting block that facilitates the rearrangement of electrical connections of the connector module in a simple, positive manner, even by unskilled persons.